
/*
 * Copyright 2002-2021 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 *版权所有2002-2021原作者。
 *
 *根据Apache许可证2.0版（“许可证”）许可；
 *除非符合许可证的规定，否则您不得使用此文件。
 *您可以在以下网址获取许可证副本
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 *除非适用法律要求或书面同意，否则软件
 *根据许可证分发是在“按原样”的基础上分发的，
 *无任何明示或暗示的保证或条件。
 *有关管理权限的特定语言，请参阅许可证
 *许可证下的限制。
 */

package org.springframework.context.event;

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.Ordered;
import org.springframework.lang.Nullable;

/**
 * Extended variant of the standard {@link ApplicationListener} interface,
 * exposing further metadata such as the supported event and source type.
 *
 * <p>For full introspection of generic event types, consider implementing
 * the {@link GenericApplicationListener} interface instead.
 *
 * @author Juergen Hoeller
 * @since 3.0
 * @see GenericApplicationListener
 * @see GenericApplicationListenerAdapter
 */
/**
 *标准{@link ApplicationListener}接口的扩展变体，
 *公开进一步的元数据，例如所支持的事件和源类型。
 *
 *＜p＞要全面反省通用事件类型，请考虑实现
 *改为{@link GenericApplicationListener}接口。
 *
 *@作者Juergen Hoeller
 *@自3.0起
 *@参见GenericApplicationListener
 *@参见GenericApplicationListenerAdapter
 */
public interface SmartApplicationListener extends ApplicationListener<ApplicationEvent>, Ordered {

	/**
	 * Determine whether this listener actually supports the given event type.
	 * @param eventType the event type (never {@code null})
	 */
	/**
	 *确定此侦听器是否实际支持给定的事件类型。
	 *@param eventType事件类型（从不｛@code null｝）
	 */
	boolean supportsEventType(Class<? extends ApplicationEvent> eventType);

	/**
	 * Determine whether this listener actually supports the given source type.
	 * <p>The default implementation always returns {@code true}.
	 * @param sourceType the source type, or {@code null} if no source
	 */
	/**
	 *确定此侦听器是否真的支持给定的源类型。
	 *＜p＞默认实现总是返回｛@code true｝。
	 *@param sourceType源类型，如果没有源，则为｛@code null｝
	 */
	default boolean supportsSourceType(@Nullable Class<?> sourceType) {
		return true;
	}

	/**
	 * Determine this listener's order in a set of listeners for the same event.
	 * <p>The default implementation returns {@link #LOWEST_PRECEDENCE}.
	 */
	/**
	 *确定此侦听器在同一事件的一组侦听器中的顺序。
	 *＜p＞默认实现返回｛@link#LOWEST_PRECDENCE｝。
	 */
	@Override
	default int getOrder() {
		return LOWEST_PRECEDENCE;
	}

	/**
	 * Return an optional identifier for the listener.
	 * <p>The default value is an empty String.
	 * @since 5.3.5
	 * @see EventListener#id
	 * @see ApplicationEventMulticaster#removeApplicationListeners
	 */
	/**
	 *返回侦听器的可选标识符。
	 *＜p＞默认值是一个空字符串。
	 *@自5.3.5起
	 *@见EventListener#id
	 *@see ApplicationEventMulticast#removeApplicationListeners
	 */
	default String getListenerId() {
		return "";
	}

}
